I've been where you are lovely. I had HA for about 43 years until I grabbed that sucka by the danglers...
Anxiety generally hits the gut first - IBS.
Have you ever had a 'near miss' and felt like you've been punched in the guts? That's the fight or flight response.
If there was anything in your digestive system that shouldn't be there, the camera would have found it, and you're clear - so this is most likely IBS.
Medication can account for nausea bloating, and a whole load of unpleasant symptoms - as can anxiety itself.
Some things to try...
Look at your diet and eliminate gluten and dairy - not at the same time though - and see if there's a difference?
Drink ginger tea for nausea (it really works) and peppermint tea for bloating (also really works)
Also worth a look at your Vit B12 levels for bloating as a deficiency can cause this symptom too. As we get older our B12 levels drop - especially women so it's worth looking into..
IBS bloat is not the same as fluid and the doctors absolutely would have seen ascites, so you can forget that one..
This reads as
classic IBS lovely and nothing will change until you stop tormenting yourself with imaginary diseases and start to get proactive on the anxiety.